This invention relates generally to phase change memories.
Phase change memory devices use phase change materials, i.e., materials that may be electrically switched between a generally amorphous and a generally crystalline state, for electronic memory application. One type of memory element utilizes a phase change material that may be, in one application, electrically switched between a structural state of generally amorphous and generally crystalline local order or between different detectable states of local order across the entire spectrum between completely amorphous and completely crystalline states. The state of the phase change materials is also non-volatile in that, when set in either a crystalline, semi-crystalline, amorphous, or semi-amorphous state representing a resistance value, that value is retained until changed by another programming event, as that value represents a phase or physical state of the material (e.g., crystalline or amorphous). The state is unaffected by removing electrical power.
Conventionally, electrical energy is used to heat the phase change material and to cause the phase change material to transform between amorphous and crystalline phases. The phase change material may be fabricated within a pore filled with a chalcogenide material as one example. The volume of the pore defines the material that must change phase. The greater the volume of material that must change phase, the more electrical energy is required by the cell and the higher its power dissipation.
Thus, there is a need for better ways to convert phase change memories between phases.